The invention relates generally to the field of the indication of solid tumors. It is well known that metastasis of solid tumors is the main reason for the high mortality rate from cancer. It is caused by cells which are disseminated in the lymph nodes and/or circulate in the peripheral blood. Some of the circulating tumor cells can, under certain circumstances, reach remote compartments where they begin to grow again. In the case of a number of tumors, these compartments are known. In breast cancer and cancer of the colon, one such compartment is the bone marrow. The incidence of the tumor cells in relation to normal bone marrow cells is at most 10−3 to 10−7 tumor cells/normal bone marrow cells. To obtain samples for bone marrow diagnosis, a special procedure is required in combination with or following an operation. Regular monitoring would require repetition of this procedure. Given the inconvenience this causes to the patient and the expenditure in terms of cost and time, it is sought to keep the number of surgical procedures as low as possible.
A further possibility is to examine the peripheral blood, which is much easier to access. However, the problem in this case is that detectable tumor cells in the peripheral blood are present only in extremely small numbers. Another difficulty is that the tumor cells circulating in the peripheral blood can contaminate the transplant in high-dose chemotherapy or autologous peripheral blood stem cell transplantation. Systems with a high level of sensitivity are therefore required to detect such a small number of residual tumor cells.
From U.S. Pat. No. 6,365,362 B1 a highly sensitive assay is known which combines immunomagnetic enrichment with multiparameter flow cytometric and immunocytochemical analysis to detect, enumerate and characterize carcinoma cells in the blood.
From EP 1 262 776 A2 a method for quantitative detection of vital epithelial tumor cells in a body fluid is known. This method comprises obtaining a defined quantity of a body fluid, labeling the vital epithelial tumor cells by addition of an antihuman epithelial antibody bound to magnetic particles, labeling the vital epithelial tumor cells by addition of antihuman epithelial antibodies bound to a fluorochrome, magnetically enriching the vital epithelial tumor cells, immobilizing the suspension so obtained on a support material, recording the vital epithelial tumor cells by means of laser scanning cytometry, and calculating the number of the cells in relation to the quantity of body fluid initially obtained.